00008889552012-06-302012-06-300000888955ntfi:S000009135Member2012-06-302012-06-300000888955ntfi:S000009135Memberntfi:C000024848Member2012-06-302012-06-300000888955ntfi:S000009135Memberntfi:C000024845Member2012-06-302012-06-300000888955ntfi:S000009135Memberntfi:C000024846Member2012-06-302012-06-300000888955ntfi:S000009135Memberntfi:C000024847Member2012-06-302012-06-300000888955ntfi:S000009135Memberrr:AfterTaxesOnDistributionsMemberntfi:C000024848Member2012-06-302012-06-300000888955ntfi:S000009135Memberrr:AfterTaxesOnDistributionsAndSalesMemberntfi:C000024848Member2012-06-302012-06-300000888955ntfi:S000009135Memberntfi:index_Barclays_Capital_Quality_Intermediate_Municipal_Bond_Index_This_index_of_municipal_bonds_of_issuers_throughout_the_US_is_unmanaged_and_does_not_reflect_deductions_for_fund_operating_expensMember2012-06-302012-06-30xbrli:pureiso4217:USDPurchases of $1 million or more have no sales charge but a contingent deferred sales charge of up to 1% for redemptions within two years of purchase and up to 0.50 of 1% for redemptions during the third and fourth years after purchase.The Manager has contractually undertaken to waive fees and/or reimburse Fund expenses so that total Fund expenses will not exceed 0.83% for Class A Shares, 1.68% for Class C Shares, 0.98% for Class I Shares or 0.68% for Class Y Shares. These expense limitations are in effect until October 31, 2013. Prior to October 31, 2013, the Manager may not terminate the arrangement without the approval of the Board of Trustees.The Distribution Plan for Class I Shares permits payment of a distribution fee of up to 0.25%. The Board of Trustees currently authorizes payment of a distribution fee of 0.15% for Class I Shares.AQUILA NARRAGANSETT TAX-FREE INCOME FUNDOtherfalse00008889552012-06-302012-10-252012-10-252012-10-25Aquila Narragansett Tax-Free Income FundFund Performance<div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund&#8217;s performance from year to year and by showing how the Fund&#8217;s average annual total returns for the designated periods compare with those of a broad measure of market performance. The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future. Updated performance information is available at <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt; TEXT-DECORATION: underline">www.aquilafunds.com</font> or by calling <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-WEIGHT: bold">800-437-1020 (toll-free).</font></font> </div>ANNUAL TOTAL RETURNS - As of December 31 Class Y Shares - 2002 - 20110.09410.05660.03290.02230.03530.03790.01460.07070.01880.0733~ http://aquilafunds.com/20121025/role/ScheduleAnnualTotalReturnsBarChart20005 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact ntfi_C000024848Member row primary compact * ~highest return for a quarter0.04452002-09-30lowest return for a quarter-0.02502004-06-30The year-to-date (from January 1, 2012 to September 30, 2012) total return for Class Y Shares was0.04082012-09-30<div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 39.45pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-12" style="MARGIN-LEFT: 36pt"></font>During the 10-year period shown in the bar chart, the highest return for a quarter was 4.45% (quarter ended September 30, 2002) and the lowest return for a quarter was &#8211;2.50% (quarter ended June 30, 2004).</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-13" style="MARGIN-LEFT: 36pt"></font>The year-to-date (from January 1, 2012 to September 30, 2012) total return for Class Y Shares was 4.08%.</font> </div>0.02910.03270.03950.05140.03240.03490.06900.03970.04280.07330.04280.04540.07330.04270.04520.06120.04210.04460.08550.05680.0506~ http://aquilafunds.com/20121025/role/ScheduleAverageAnnualReturnsTransposed20006 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact * column rr_PerformanceMeasureAxis compact * row primary compact * ~<div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-14" style="MARGIN-LEFT: 36pt"></font>These returns are calculated using the highest individual Federal marginal income and capital gains tax rates in effect at the time of each distribution and redemption, but do not reflect state and local taxes.&#160;&#160;Actual after-tax returns will depend on your specific situation and may differ from those shown.&#160;&#160;The total returns reflect reinvestment of dividends and distributions.&#160;&#160;After-tax returns are shown only for Class Y Shares.&#160;&#160;After-tax returns for other classes of shares will vary.</font> </div> These returns are calculated using the highest individual Federal marginal income and capital gains tax rates in effect at the time of each distribution and redemption, but do not reflect state and local taxesThe following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund's performance from year to year and by showing how the Fund's average annual total returns for the designated periods compare with those of a broad measure of market performance.The Fund's past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.After-tax returns are shown only for Class Y Shares. After-tax returns for other classes of shares will vary.This index of municipal bonds of issuers throughout the U.S. is unmanaged and does not reflect deductions for fund operating expenses, taxes or sales charges.800-437-1020www.aquilafunds.com Average Annual Total Returns for the Periods Ended December 31, 2011Actual after-tax returns will depend on your specific situation and may differ from those shown.Principal Risks<div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-1" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Market and Interest Rate Risk</font>. The market prices of the Fund&#8217;s securities may go up or down, sometimes rapidly or unpredictably, due to general market conditions, such as real or perceived adverse economic or political conditions, inflation, changes in interest rates, lack of liquidity in the bond markets or adverse investor sentiment. When market prices fall, the value of your investment may go down. The value of your investment may also go down when interest rates rise. A rise in rates tends to have a greater impact on the prices of longer term securities.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-2" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Credit Risk</font>. If an issuer or obligor of a security held by the Fund or a counterparty to a financial contract with the Fund defaults or is downgraded, or if the value of the assets underlying a security declines, the value of your investment will typically decline.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-3" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Rating Agency Risk</font>: Investment grade debt securities may be downgraded by a major rating agency to below investment grade status, which would increase the risk of holding these securities. In addition, a rating may become stale in that it fails to reflect changes to an issuer&#8217;s financial condition. Ratings represent the rating agency&#8217;s opinion regarding the quality of the security and are not a guarantee of quality. Rating agencies may fail to make timely credit ratings in response to subsequent events. In addition, ratings agencies are subject to an inherent conflict of interest because they are often compensated by the same issuers whose securities they grade.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-4" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Risks Associated with Investments in Rhode Island and Other Municipal Obligations</font>. The Fund may be affected significantly by adverse economic, political or other events affecting Rhode Island and other municipal issuers.&#160;&#160;Municipal issuers may be adversely affected by rising health care costs, increasing unfunded pension liabilities, and by the phasing out of federal programs providing financial support.&#160;&#160;Unfavorable conditions and developments relating to projects financed with municipal securities can result in lower revenues to issuers of municipal securities.&#160;&#160;Issuers often depend on revenues from these projects to make principal and interest payments.&#160;&#160;The value of municipal securities also can be adversely affected by changes in the financial condition of one or more individual municipal issuers or insurers of municipal issuers, regulatory developments, legislative actions, and by uncertainties and public perceptions concerning these and other factors.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-5" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Tax Risk</font>. The income on the Fund&#8217;s Rhode Island Obligations and other municipal obligations could become subject to Federal and/or state income taxes due to noncompliant conduct by issuers, unfavorable legislation or litigation or adverse interpretations by regulatory authorities.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-6" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Liquidity Risk</font>. Some securities held by the Fund may be difficult to sell, or illiquid, particularly during times of market turmoil. Illiquid securities may also be difficult to value. If the Fund is forced to sell an illiquid security to meet redemption requests or other cash needs, the Fund may be forced to sell the security at a loss.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-7" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Prepayment or Call Risk</font>. Many issuers have a right to prepay their securities. If interest rates fall, an issuer may exercise this right, and the Fund could be forced to reinvest prepayment proceeds at a time when yields on securities available in the market are lower than the yield on the prepaid security. The Fund may also lose any premium it paid on the security.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-8" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-WEIGHT: bold">Portfolio Selection Risk</font>. The value of your investment may decrease if the Sub-Adviser&#8217;s judgment about the quality, relative yield, value or market trends affecting a particular security, industry, sector or region, or about interest rates, is incorrect.</font> </div> <br/><div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">An investment in the Fund is not a deposit in RBS Citizens, N.A., any of its bank or non-bank affiliates or any other bank, and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-9" style="MARGIN-LEFT: 36pt"></font>The Fund is classified as a &#8220;non-diversified&#8221; investment company under the Investment Company Act of 1940 (the &#8220;1940 Act&#8221;). Thus, compared with &#8220;diversified&#8221; funds, it may invest a greater percentage of its assets in obligations of a small number of issuers. In general, the more the Fund invests in the securities of specific issuers or issues of a similar project type, the more the Fund is exposed to risks associated with investments in those issuers or types of projects.&#160;&#160;Also, the Fund may be more volatile than a more geographically diverse fund.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-10" style="MARGIN-LEFT: 36pt"></font>Loss of money is a risk of investing in the Fund.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-11" style="MARGIN-LEFT: 36pt"></font>These risks are discussed in more detail later in the Prospectus or in the SAI.</font> </div>Loss of money is a risk of investing in the Fund.The Fund is classified as a "non-diversified" investment company under the Investment Company Act of 1940 (the "1940 Act"). Thus, compared with "diversified" funds, it may invest a greater percentage of its assets in obligations of a small number of issuers. In general, the more the Fund invests in the securities of specific issuers or issues of a similar project type, the more the Fund is exposed to risks associated with investments in those issuers or types of projects. Also, the Fund may be more volatile than a more geographically diverse fund.An investment in the Fund is not a deposit in RBS Citizens, N.A., any of its bank or non-bank affiliates or any other bank, and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.Investment Objective<div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">The Fund&#8217;s objective is to provide you as high a level of current income exempt from Rhode Island state and regular Federal income taxes as is consistent with preservation of capital.</font> </div>Principal Investment Strategies<div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1" style="MARGIN-LEFT: 36pt"></font><font style="DISPLAY: inline; FONT-FAMILY: Times New Roman">The</font> Fund invests primarily in tax-free municipal obligations that pay interest exempt, in the opinion of bond counsel, from Rhode Island state and reg<font style="DISPLAY: inline; FONT-FAMILY: Times New Roman">ular Federal income taxes. In general, all or almost all of</font> these obligations are issued by the State of Rhode Island, its counties and various other local authorities. <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman">We call these &#8220;Rhode Island Obligations.&#8221;</font> These securities may include participation or other interests in municipal securities and variable rate demand notes.&#160;&#160;Some Rhode Island Obligations, such as general obligation issues, are backed by the issuer&#8217;s taxing authority, while other Rhode Island Obligations, such as revenue bonds, are backed only by revenues from certain facilities or other sources and not by the issuer itself.</font> </div> <br/><div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt"><font id="TAB1-0" style="MARGIN-LEFT: 36pt"></font>Under normal circumstances, at least 80% of the Fund&#8217;s net assets will consist of Rhode Island Obligations the income paid upon which will not be subject to the Federal alternative minimum tax on individuals.&#160;&#160;These obligations can be of any maturity, but the Fund&#8217;s average portfolio maturity goal has traditionally been between 10 and 12 years.</font> </div> <br/><div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">At the time of purchase, the Fund&#8217;s Rhode Island Obligations must be of investment grade quality. This means that they must either</font> </div> <br/><table cellpadding="0" cellspacing="0" id="list" width="100%" style="FONT-FAMILY: times new roman; FONT-SIZE: 10pt; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"> <tr valign="top"> <td align="right" style="WIDTH: 54pt"> <div> <font style="display: inline; font-size: 10pt; font-family: Symbol, serif;">&#183;&#160;&#160;</font> </div> </td> <td> <div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">be rated within the four highest credit ratings assigned by nationally recognized statistical rating organizations or,</font> </div> </td> </tr> </table> <br/><table cellpadding="0" cellspacing="0" id="list-0" width="100%" style="FONT-FAMILY: times new roman; FONT-SIZE: 10pt; FONT-SIZE: 10pt; FONT-FAMILY: times new roman"> <tr valign="top"> <td align="right" style="WIDTH: 54pt"> <div> <font style="display: inline; font-size: 10pt; font-family: Symbol, serif;">&#183;&#160;&#160;</font> </div> </td> <td> <div style="TEXT-INDENT: 0pt; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">if unrated, be determined to be of comparable quality by the Fund&#8217;s Sub-Adviser, Citizens Investment Advisors, a department of RBS Citizens, N.A.</font> </div> </td> </tr> </table> <br/><div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">The Sub-Adviser selects obligations for the Fund&#8217;s portfolio to best achieve the Fund&#8217;s objective by considering various characteristics including quality, maturity and coupon rate.</font> </div>Example<div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds.</font> </div> <br/><div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year and that the Fund&#8217;s operating expenses remain the same. Six years after the date of purchase, Class C Shares automatically convert to Class A Shares. Although your actual costs may be higher or lower, based on these assumptions your costs would be:</font> </div>481663859142627153893015941003215591244692263978911715389301594~ http://aquilafunds.com/20121025/role/ScheduleExpenseExampleTransposed20003 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact * row primary compact * ~~ http://aquilafunds.com/20121025/role/ScheduleExpenseExampleNoRedemptionTransposed20004 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact * row primary compact * ~You would pay the following expenses if you did not redeem your Class C Shares:Portfolio Turnover<div style="TEXT-INDENT: 36pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="justify"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">The Fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in annual Fund operating expenses or in the example, affect the Fund's performance. During the most recent fiscal year, the Fund's portfolio turnover rate was 11% of the average value of its portfolio.</font> </div>0.11Fees and Expenses of the Fund<div style="TEXT-INDENT: 0pt; DISPLAY: block; MARGIN-LEFT: 0pt; MARGIN-RIGHT: 0pt" align="left"> <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman; FONT-SIZE: 10pt">This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. You may qualify for sales <font style="DISPLAY: inline; FONT-FAMILY: Times New Roman">charge</font> discounts if you and your immediate family invest, or agree to invest in the future, at least $25,000 in the Fund or in other funds in the Aquila Group of Funds. More information about these and other discounts, as well as eligibility requirements for each share class, is available from your financial advisor and in "Alternative Purchase Plans&#8221; on page 21 of the Fund's Prospectus, "What are the sales charges for purchases of Class A Shares&#8221; on page 22 of the Prospectus, "Reduced Sales Charges for Certain Purchases of Class A Shares&#8221; on page 24 of the Prospectus<font style="DISPLAY: inline; FONT-FAMILY: Times New Roman">, and &#8220;Purchase, Redemption, and Pricing of Shares&#8221; on page 44 of the Statement of Additional Information (the &#8220;SAI&#8221;).</font></font> </div>0.04000.00000.00000.00000.00000.01000.00000.00000.00500.00500.00500.00500.00150.00750.00150.00000.00220.00470.00370.00220.00870.01720.01020.0072-0.0004-0.0004-0.0004-0.00040.00830.01680.00980.0068~ http://aquilafunds.com/20121025/role/ScheduleShareholderFees20001 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact * row primary compact * ~~ http://aquilafunds.com/20121025/role/ScheduleOperatingExpenses20002 column dei_LegalEntityAxis compact ntfi_S000009135Member column rr_ProspectusShareClassAxis compact * row primary compact * ~2013-10-31You may qualify for sales charge discounts if you and your immediate family invest, or agree to invest in the future, at least $25,000 in the Fund or in other funds in the Aquila Group of Funds.Annual Fund Operating Expenses (Expenses that you pay each year as a percentage of your investment)25000 Purchases of $1 million or more have no sales charge but a contingent deferred sales charge of up to 1% for redemptions within two years of purchase and up to 0.50 of 1% for redemptions during the third and fourth years after purchase. Shareholder Fees (fees paid directly from your investment)